Tool for controlling base plate gradient of cable trench and wiping and pressing trench-in-trench and application method of tool

The invention discloses a tool for controlling the base plate gradient of a cable trench and wiping and pressing a trench-in-trench and an application method of the tool and relates to the field of construction of the cable trench of a transformer substation. At present, construction units have no unified technological standards for construction of the trench-in-trench; construction tools for small trenches are not unified; elevation control and gradient control are not precise. The tool disclosed by the invention comprises bracket rods, gradient control rods, grounded rods and operating handles, wherein four bracket rods are arranged; two bracket rods are connected with one grounded rod which is positioned between the bracket rods to form a bracket; two brackets are arranged bilaterally; the gradient control rods are arranged between the two brackets to form a gradient control frame; the bracket rods are vertically arranged; the gradient control rods are obliquely arranged at the middle lower parts of the tw